BME680 Air Quality low?

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I might try to wrangle it into a blog post and then cross-link it from the product page and the tutorial.

I think from a very basic point of view, run the sensor for 24 hours reading the raw resistance values, as you are, look at the data, and then decide where to set the baseline. That’s a more sensible way than relying on the way that my script does it.

So, essentially, it would be:

#!/usr/bin/env python

import bme680
import time

sensor = bme680.BME680()

sensor.set_humidity_oversample(bme680.OS_2X)
sensor.set_pressure_oversample(bme680.OS_4X)
sensor.set_temperature_oversample(bme680.OS_8X)
sensor.set_filter(bme680.FILTER_SIZE_3)
sensor.set_gas_status(bme680.ENABLE_GAS_MEAS)

sensor.set_gas_heater_temperature(320)
sensor.set_gas_heater_duration(150)
sensor.select_gas_heater_profile(0)

start_time = time.time()
curr_time = time.time()

try:
    gas_baseline = INSERT_BASELINE_VALUE_HERE
    hum_weighting = 0.25

    while True:
        if sensor.get_sensor_data() and sensor.data.heat_stable:
            gas = sensor.data.gas_resistance
            gas_offset = gas_baseline - gas

            hum = sensor.data.humidity
            hum_offset = hum - hum_baseline

            if hum_offset > 0:
                hum_score = (100 - hum_baseline - hum_offset) / (100 - hum_baseline) * (hum_weighting * 100)

            else:
                hum_score = (hum_baseline + hum_offset) / hum_baseline * (hum_weighting * 100)

            if gas_offset > 0:
                gas_score = (gas / gas_baseline) * (100 - (hum_weighting * 100))

            else:
                gas_score = 100 - (hum_weighting * 100)

            air_quality_score = hum_score + gas_score

            print("Gas: {0:.2f} Ohms,humidity: {1:.2f} %RH,air quality: {2:.2f}".format(gas, hum, air_quality_score))
            time.sleep(1)

except KeyboardInterrupt:
    pass
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